serial: sc16is7xx: improve do/while loop in sc16is7xx_irq()

Simplify and improve readability by replacing while(1) loop with
do {} while, and by using the keep_polling variable as the exit
condition, making it more explicit.

Fixes: 8344498 ("sc16is7xx: Fix for multi-channel stall")
Cc:  <[email protected]>
Suggested-by: Andy Shevchenko <[email protected]>
Signed-off-by: Hugo Villeneuve <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: hvilleneuvedoo

drivers/tty/serial/sc16is7xx.c

@@ -783,17 +783,18 @@ static bool sc16is7xx_port_irq(struct sc16is7xx_port *s, int portno)
 
 static irqreturn_t sc16is7xx_irq(int irq, void *dev_id)
 {
+	bool keep_polling;
+
 	struct sc16is7xx_port *s = (struct sc16is7xx_port *)dev_id;
 
-	while (1) {
-		bool keep_polling = false;
+	do {
 		int i;
 
+		keep_polling = false;
+
 		for (i = 0; i < s->devtype->nr_uart; ++i)
 			keep_polling |= sc16is7xx_port_irq(s, i);
-		if (!keep_polling)
-			break;
-	}
+	} while (keep_polling);
 
 	return IRQ_HANDLED;
 }